-LRB- CNN -RRB- -- The FBI 's Ten Most Wanted list now includes a man suspected of killing a young New York mother and her toddler son execution-style in 2010 .

Juan Elias Garcia , who the FBI calls an `` enthusiastic murderer , '' now has a $ 100,000 reward on his head .

`` Garcia 's callous disregard for human life resulted in the senseless murder of a young mother and her helpless 2-year-old son , '' said George Venizelos , assistant director in charge of the FBI 's New York Field Office , on the agency 's website .

Garcia is alleged to be a member of the violent MS-13 , or Mara Salvatrucha , gang . He 's thought to be hiding in El Salvador .

The FBI said a romantic entanglement and gang rivalries lay at the heart of slayings .

Slaying victim Vanessa Argueta , 19 , is said to have had a romantic relationship with Garcia -- and she 's also believed to have had ties to two rival gangs : the 18th Street gang and the Latin Kings .

`` They were going to kill her for disrespecting the gang , '' said Special Agent James Lopez in the FBI release . `` It is unacceptable for MS-13 members to have girls they associate with be involved with rival gang members . ''

The FBI said that under the guise of an invitation to dinner in Central Islip , New York , Garcia coerced Argueta and her 2-year-old son into the woods . There , they were met by two co-conspirators -- members of Mara Salvatrucha -- and Argueta was murdered in front of her son . The FBI said the same gun was then used to kill the little boy .

Considered armed and dangerous , Garcia is 5 foot , 4 inches and weighs 125 pounds . He was 17 and answered to the nickname `` Cruzito '' at the time of the slayings on February 4 , 2010 .

`` His appointment to the FBI 's Top Ten list illustrates not only the seriousness of his crimes but our commitment to seeking justice for his victims , '' said Venizelos .

The FBI requests that anyone with information on Garcia contact its New York Field Office at 212-384-1000 , a nearby law enforcement agency or U.S. Embassy or Consulate . People can also submit a tip online .

Teen accused of gunning down family ` lost sense of conscience '

CNN 's Forrest Brown contributed to this report .

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The FBI is offering a $ 100,000 reward in the case of Juan Elias Garcia

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He 's accused of killing a 19-year-old woman and her 2-year-old son

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A soured romance and gang rivalries are involved , the FBI says

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Garcia is believed to be in hiding in El Salvador